Type I Error

When testing a hypothesis, this sort of error occurs when the null hypothesis is rejected but should not be rejected. The probability that this type of error occurred is represented by the Greek letter alpha.


  • A quality engineer rejects a product as defective when in fact it is NOT defective
  • A defendant is convicted but in truth, they are innocent
  • Employees of a company assume that the company has a problem but in fact the problem does not exist